Subject: [Sigtran] ASP Capabilities value 0x2 of interworking field

From: Ilie Glib <[email-masked]>
Date: Fri, 16 Dec 2005 18:07:07 +0100

Hello Folks,

Section "3.10.9.  ASP Capabilities" of SUA RFC allows to specify the
capability of ASP/IPSP.

Could you please clarify value 0x2 of "Signalling Gateway".
In my view this value should not be possible for IPSP nor for ASP,
thus it is never visible in SUA protocol. Why should it be defined as
possible value then?

Does it make sence to have an endpoint and Relay collocated in an
IPSP, then interworking field has to combine 0x3 and 0x1 values?

Thank you in advance

Ilie

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Fri, 16 Dec 2005 11:55:11 -0700

Ilie,

Ilie Glib wrote:                                                                      (Fri, 16 Dec 2005 18:07:07)
> thus it is never visible in SUA protocol. Why should it be defined as

A relay can always be an SG (i.e. have an SS7 network connection).
SG capabilities are a superset of a relay.  (A relay does not require
an SS7 connection.)

> IPSP, then interworking field has to combine 0x3 and 0x1 values?

Relay is a superset of an endpoint capability.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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From: Ilie Glib <[email-masked]>
Date: Mon, 19 Dec 2005 10:48:15 +0100

Hello Brian,

thank you for your answer.

I see some contradictions in your answer. According to your claims
Endpoint  <= Relay  <= SG.

Just for clarification, according to my understanding RKM procedures
cannot be initiated from SGPs. When a Signalling Process registers its
capabilities (RKM is the only case where ASP Capabilities are visible
in SUA), the capability of Relay means that incoming SUA messages can
be relayed after AMF to a SUA peer instance. Please note that GTT can
be part of SUA Relay. So from this point of view the Relay is not part
of GW function, although GTT is. In this sense the description in
"1.3.1.2.  Signalling Gateway as relay-point" is not consistent.

Accoding to my understanding the Endpoint can be (served) by ASP, or
IPSP, the Relay can be IPSP, ASP, and finaly the SG can be served by
SGP only.

If we look at this from viewpoint of applicability of SUA procedures
and functionalities then it is hard to agree with your statement. I
can agree that the Relay is a supperset of the Endpoint (signalling
relay points do not have usually SCCP users, but it is rather a matter
of agreement). I cannot agree that SG is a supperset of the Relay,
since procedural behaviour of these entities is very much different.

Regards

Ilie

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 19 Dec 2005 03:38:46 -0700

Ilie,

An SG supports SS7 interfaces, a Relay does not (necessarily).

--brian

Ilie Glib wrote:                       (Mon, 19 Dec 2005 10:48:15)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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From: Ilie Glib <[email-masked]>
Date: Mon, 19 Dec 2005 12:39:07 +0100

Brian,

could you please answer the following questions

1) Can SG register via RKM? If not, why the value 0x2 that indicates
Signalling Gateway?

2) Is there any difference between capabilities 0x0 and 0x1 in SUA

     0x0 indicates no interworking with SS7 Networks.
     0x1 indicates IP Signalling Endpoint (ASP), interworking with SS7
        networks.

I was more after a definition of the Relay capability in SUA
framework. Although SUA RFC mentions Relay and describes it, the
definition of Relay is missing.

Thank you in advance

Ilie

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 19 Dec 2005 04:55:57 -0700

Ilie,

Ilie Glib wrote:                                                      (Mon, 19 Dec 2005 12:39:07)
> 1) Can SG register via RKM? If not, why the value 0x2 that indicates

You are confused.  0x2 indicates signalling gateway capability: i.e.,
the registering node has an SS7 network interfaces and behaves as an
SG when interworking to that interface.

>      0x1 indicates IP Signalling Endpoint (ASP), interworking with SS7

Yes, one supports interworking with SS7 networks and the other does not.

> definition of Relay is missing.

See SCCP specifications for a definition of a relay node.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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From: Ilie Glib <[email-masked]>
Date: Mon, 19 Dec 2005 13:17:19 +0100

Brian,

I am sorry I was not clear enough. My claim was

Registration Request (REG REQ) cannot be sent from an SGP, therefore
the value 0x2 indicating signalling gateway capability is meaningless,
unless IPSP and SGP functions can be combined in one Signalling
Process.

Can an SGP act as an IPSP?

Thank you

Ilie

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 19 Dec 2005 05:37:04 -0700

Ilie,

The signalling gateway capability, SS7 interworking and relay capabilities
can be combined into any process (ASP, ISPS, SGP).

--brian

Ilie Glib wrote:                                                      (Mon, 19 Dec 2005 13:17:19)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/